JS: allow to omit delegated constructor call for external classes in common FE. Prohibit delegated constructor call for external classes in JS FE.

js/js.frontend/src/org/jetbrains/kotlin/js/resolve/diagnostics/DefaultErrorMessagesJs.kt

@@ -75,10 +75,13 @@ private val DIAGNOSTIC_FACTORY_TO_RENDERER by lazy {
         put(ErrorsJs.INLINE_EXTERNAL_DECLARATION, "Inline external declaration")
         put(ErrorsJs.NON_ABSTRACT_MEMBER_OF_EXTERNAL_INTERFACE,
             "Only nullable properties of external interfaces are allowed to be non-abstract")
+
         put(ErrorsJs.WRONG_BODY_OF_EXTERNAL_DECLARATION, "Wrong body of external declaration. Must be either ' = noImpl' or { noImpl }")
         put(ErrorsJs.WRONG_INITIALIZER_OF_EXTERNAL_DECLARATION, "Wrong initializer of external declaration. Must be ' = noImpl'")
         put(ErrorsJs.WRONG_DEFAULT_VALUE_FOR_EXTERNAL_FUN_PARAMETER,
             "Wrong default value for parameter of external function. Must be ' = noImpl'")
+        put(ErrorsJs.EXTERNAL_DELEGATED_CONSTRUCTOR_CALL, "Delegated constructor call in external class")
+        put(ErrorsJs.EXTERNAL_DELEGATION, "Using delegate on external declaration")
 
         this
     }

js/js.frontend/src/org/jetbrains/kotlin/js/resolve/diagnostics/ErrorsJs.java

@@ -80,9 +80,13 @@ public interface ErrorsJs {
             ERROR, PositioningStrategies.DECLARATION_SIGNATURE_OR_DEFAULT);
     DiagnosticFactory0<KtExpression> NON_ABSTRACT_MEMBER_OF_EXTERNAL_INTERFACE = DiagnosticFactory0.create(
             ERROR, PositioningStrategies.DECLARATION_SIGNATURE_OR_DEFAULT);
+
+    // Diagnostics about exposing implementation detail in external declarations
     DiagnosticFactory0<KtExpression> WRONG_BODY_OF_EXTERNAL_DECLARATION = DiagnosticFactory0.create(ERROR);
     DiagnosticFactory0<KtExpression> WRONG_INITIALIZER_OF_EXTERNAL_DECLARATION = DiagnosticFactory0.create(ERROR);
     DiagnosticFactory0<KtExpression> WRONG_DEFAULT_VALUE_FOR_EXTERNAL_FUN_PARAMETER = DiagnosticFactory0.create(ERROR);
+    DiagnosticFactory0<KtElement> EXTERNAL_DELEGATED_CONSTRUCTOR_CALL = DiagnosticFactory0.create(ERROR);
+    DiagnosticFactory0<KtElement> EXTERNAL_DELEGATION = DiagnosticFactory0.create(ERROR);
 
     @SuppressWarnings("UnusedDeclaration")
     Object _initializer = new Object() {

js/js.frontend/src/org/jetbrains/kotlin/js/resolve/diagnostics/JsExternalChecker.kt

@@ -91,6 +91,7 @@ object JsExternalChecker : SimpleDeclarationChecker {
         }
 
         checkBody(declaration, descriptor, diagnosticHolder, bindingContext)
+        checkDelegation(declaration, descriptor, diagnosticHolder)
     }
 
     private fun checkBody(
@@ -114,6 +115,34 @@ object JsExternalChecker : SimpleDeclarationChecker {
         }
     }
 
+    private fun checkDelegation(declaration: KtDeclaration, descriptor: DeclarationDescriptor, diagnosticHolder: DiagnosticSink) {
+        if (descriptor !is MemberDescriptor || !DescriptorUtils.isEffectivelyExternal(descriptor)) return
+
+        if (declaration is KtClassOrObject) {
+            for (superTypeEntry in declaration.superTypeListEntries) {
+                when (superTypeEntry) {
+                    is KtSuperTypeCallEntry -> {
+                        diagnosticHolder.report(ErrorsJs.EXTERNAL_DELEGATED_CONSTRUCTOR_CALL.on(superTypeEntry.valueArgumentList!!))
+                    }
+                    is KtDelegatedSuperTypeEntry -> {
+                        diagnosticHolder.report(ErrorsJs.EXTERNAL_DELEGATION.on(superTypeEntry))
+                    }
+                }
+            }
+        }
+        else if (declaration is KtSecondaryConstructor) {
+            val delegationCall = declaration.getDelegationCall()
+            if (!delegationCall.isImplicit) {
+                diagnosticHolder.report(ErrorsJs.EXTERNAL_DELEGATED_CONSTRUCTOR_CALL.on(delegationCall))
+            }
+        }
+        else if (declaration is KtProperty && descriptor !is PropertyAccessorDescriptor) {
+            declaration.delegate?.let { delegate ->
+                diagnosticHolder.report(ErrorsJs.EXTERNAL_DELEGATION.on(delegate))
+            }
+        }
+    }
+
     private fun isDirectlyExternal(declaration: KtDeclaration, descriptor: DeclarationDescriptor): Boolean {
         if (declaration is KtProperty && descriptor is PropertyAccessorDescriptor) return false